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Abstract:

A casing check valve for providing isolation of an open hole section of a
wellbore from a cased hole section of the wellbore is described herein.
The casing check valve can include a housing and an actuating sleeve
movably disposed within the housing between an actuated position and a
normal position. The housing can include a housing body, at least one
actuating sleeve coupling feature, a flapper assembly, a flapper seat,
and at least one casing pipe coupling feature. The actuating sleeve can
include an actuating sleeve body, at least one housing coupling feature,
at least one operating tool coupling feature, and a distal extension.

Claims:

1. A casing check valve for providing isolation of an open hole section
of a wellbore from a cased hole section of the wellbore, the casing check
valve comprising: a housing comprising: a housing body forming a housing
cavity that traverses therethrough, wherein the housing body comprises a
top portion, a middle portion, and a bottom portion; at least one
actuating sleeve coupling feature disposed on an inner surface of the
middle portion of the housing body; a flapper assembly disposed along the
inner surface of the bottom portion of the housing body; a flapper seat
disposed on the inner surface of the bottom portion of the housing body
adjacent to the flapper assembly; and a first casing pipe coupling
feature disposed on the top portion of the housing body, wherein the
first casing pipe coupling feature is configured to couple to a first
casing pipe; and an actuating sleeve disposed within the housing cavity
between an actuated position and a normal position, wherein the actuating
sleeve is concentric with and adjacent to the housing, wherein the
actuating sleeve comprises: an actuating sleeve body forming an actuating
sleeve cavity; at least one housing coupling feature disposed on an outer
surface of the actuating sleeve, wherein the at least one housing
coupling feature is removably coupled to the at least one actuating
sleeve coupling feature of the housing as the actuating sleeve moves
between the actuated position and the normal position; at least one
operating tool coupling feature configured to receive a complementary
coupling feature of an operating tool disposed within the actuating
sleeve cavity; and a distal extension that extends from a distal end of
the actuating sleeve body, wherein the distal extension opens the flapper
assembly when the actuating sleeve is in the actuated position, and
wherein the distal extension allows the flapper to close when the
actuating sleeve is in the normal position.

2. The casing check valve of claim 1, further comprising: a second casing
pipe coupling feature disposed on the bottom portion of the housing body,
wherein the second casing pipe coupling feature is configured to couple
to a second casing pipe.

3. The casing check valve of claim 1, wherein the housing further
comprises: a stop feature disposed on an inner surface of the housing.

4. The casing check valve of claim 3, wherein the stop feature positions
the actuating sleeve in the actuated position.

6. The casing check valve of claim 1, wherein the housing further
comprises: a stop feature disposed on an inner surface of the housing,
wherein the stop feature is disposed where the top portion and the middle
portion of the housing body adjoin, wherein the stop feature positions
the actuating sleeve in the normal position.

8. The casing check valve of claim 7, wherein the actuating sleeve is in
the normal position when the at least one first housing coupling feature
is coupled to a first actuating sleeve coupling feature of the plurality
of actuating sleeve coupling features, and wherein the actuating sleeve
is in the actuated position when the at least one first housing coupling
feature is coupled to a second actuating sleeve coupling feature of the
plurality of actuating sleeve coupling features.

9. The casing check valve of claim 8, wherein the second actuating sleeve
coupling feature is disposed closer to the bottom portion of the housing
than the first actuating sleeve coupling feature.

10. The casing check valve of claim 8, wherein the at least one housing
coupling feature is a collet that protrudes from the actuating sleeve
body, and wherein the first actuating sleeve coupling feature and the
second actuating sleeve coupling feature are recesses having a shape and
a size to receive the collet.

11. The casing check valve of claim 1, wherein the at least one actuating
sleeve coupling feature comprises mating threads disposed on the inner
surface of the middle portion of the housing body, and wherein the at
least one housing coupling feature comprises complementary mating threads
disposed on the outer surface of the actuating sleeve body.

12. The casing check valve of claim 11, wherein the actuating sleeve is
in the normal position when the complementary mating threads are coupled
to a first portion of the mating threads when the actuating sleeve is in
the normal position, and wherein the actuating sleeve is in the normal
position when the complementary mating threads are coupled to a second
portion of the mating threads when the actuating sleeve is in the
actuated position.

13. The casing check valve of claim 1, wherein the flapper assembly
comprises a hinge that moves a flapper between an open position and a
closed position.

14. The casing check valve of claim 13, wherein the bottom portion of the
housing body comprises a recessed area, wherein the paddle is positioned
within the recessed area when the paddle is in the open position.

15. The casing check valve of claim 13, wherein the paddle is moved to
the open position by the distal extension of the actuating sleeve when
the actuating sleeve is in the actuated position.

16. A casing check valve system for providing isolation within a
wellbore, the casing check valve system comprising: a casing string
disposed in a wellbore, wherein the casing string comprises a plurality
of casing pipe; an operational string comprising an operating tool,
wherein the operating tool comprises at least one complementary coupling
feature; a casing check valve coupled to a first casing pipe, wherein the
casing check valve comprises: a housing comprising: a housing body
forming a housing cavity that traverses therethrough, wherein the housing
body comprises a top portion, a middle portion, and a bottom portion; at
least one actuating sleeve coupling feature disposed on an inner surface
of the middle portion of the housing body; a flapper assembly disposed
along the inner surface of the bottom portion of the housing body; a
flapper seat disposed on the inner surface of the bottom portion of the
housing body adjacent to the flapper assembly; and a first casing pipe
coupling feature disposed on the top portion of the housing body, wherein
the first casing pipe coupling feature couples to a first casing pipe of
the plurality of casing pipe; and an actuating sleeve disposed within the
housing cavity between an actuated position and a normal position,
wherein the actuating sleeve is concentric with and adjacent to the
housing, wherein the actuating sleeve comprises: an actuating sleeve body
forming an actuating sleeve cavity, inside of which the operational
string is disposed; at least one housing coupling feature disposed on an
outer surface of the actuating sleeve, wherein the at least one housing
coupling feature is removably coupled to the at least one actuating
sleeve coupling feature of the housing as the actuating sleeve moves
between the actuated position and the normal position; at least one
operating tool coupling feature that receives the at least one
complementary coupling feature of the operating tool disposed within the
sleeve cavity; and a distal extension that extends from a distal end of
the actuating sleeve body, wherein the distal extension opens the flapper
assembly when the actuating sleeve is in the actuated position, and
wherein the distal extension allows the flapper to close when the
actuating sleeve is in the normal position.

17. The system of claim 16, wherein the housing of the casing check valve
further comprises: a second casing pipe coupling feature disposed on the
bottom portion of the housing body, wherein the second casing pipe
coupling feature couples to a second casing pipe of the plurality of
casing pipe.

18. The system of claim 16, wherein the at least one complementary
coupling feature is mechanically retractable.

19. The system of claim 16, further comprising: a control unit; and a
control line coupled to the control unit and the at least one
complementary coupling feature, wherein the control unit controls
hydraulic fluid through the control line to determine a state of the at
least one complementary coupling feature.

20. A method for isolating a section of a wellbore, the method
comprising: receiving a coupling feature of an operating tool;
repositioning, based on movement of the operating tool in a direction, an
actuating sleeve within a housing body from a first position to a second
position, wherein repositioning the actuating sleeve from the first
position to the second position changes a flapper assembly from a first
state to a second state; and releasing, based on continued movement of
the operating tool in the direction, the coupling feature of the
operating tool.

Description:

TECHNICAL FIELD

[0001] The present application relates to casing valves, and in
particular, methods and systems of mechanically-operated casing check
valves.

BACKGROUND

[0002] The drilling of an oil, gas, or other type of well requires that an
upper casing string be set at some shallower depth than the total depth
of the well. Some purposes of the casing string are to protect a portion
of the wellbore environment and to protect personnel. When the casing
string is set, the drilling operation continues to extend the open hole
portion of the wellbore below the casing string. During the drilling
process, it can be necessary to pull the drill string (also called the
tubing string) out of the wellbore (a process known as "tripping") on one
or more occasions. The open hole and casing provides a hydraulic conduit
up through the wellbore that serves as a flow path with the potential
risk of flow, which can jeopardize the integrity of the wellbore and/or
present safety concerns. In other words, unless a tripping operation is
carefully controlled, the integrity of the open hole can be compromised.

[0003] A drill string can be several thousand feet long, and so performing
a tripping operation can take many hours. This time to perform a tripping
operation, as well as a subsequent reinsertion of the drill string into
the wellbore, can cost significant amounts of money without making any
progress in terms of extending the open hole portion of the wellbore.
Consequently, it is undesirable to slow the tripping process from a
financial perspective.

SUMMARY

[0004] In general, in one aspect, the disclosure relates to a casing check
valve for providing isolation of an open hole section of a wellbore from
a cased hole section of the wellbore. The casing check valve can include
a housing and an actuating sleeve. The housing of the casing check valve
can include a housing body forming a housing cavity that traverses
therethrough, where the housing body includes a top portion, a middle
portion, and a bottom portion. The housing of the casing check valve can
also include at least one actuating sleeve coupling feature disposed on
an inner surface of the middle portion of the housing body. The housing
of the casing check valve can further include a flapper assembly disposed
along the inner surface of the bottom portion of the housing body. The
housing of the casing check valve can also include a flapper seat
disposed on the inner surface of the bottom portion of the housing body
adjacent to the flapper assembly. The housing of the casing check valve
can further include a first casing pipe coupling feature disposed on the
top portion of the housing body, where the first casing pipe coupling
feature is configured to couple to a first casing pipe. The actuating
sleeve of the casing check valve can be disposed within the housing
cavity between an actuated position and a normal position, where the
actuating sleeve is concentric with and adjacent to the housing. The
actuating sleeve of the casing check valve can include an actuating
sleeve body forming an actuating sleeve cavity. The actuating sleeve of
the casing check valve can also include at least one housing coupling
feature disposed on an outer surface of the actuating sleeve, where the
at least one housing coupling feature is removably coupled to the at
least one actuating sleeve coupling feature of the housing as the
actuating sleeve moves between the actuated position and the normal
position. The actuating sleeve of the casing check valve can further
include at least one operating tool coupling feature configured to
receive a complementary coupling feature of an operating tool disposed
within the actuating sleeve cavity. The actuating sleeve of the casing
check valve can also include a distal extension that extends from a
distal end of the actuating sleeve body, where the distal extension opens
the flapper assembly when the actuating sleeve is in the actuated
position, and where the distal extension allows the flapper to close when
the actuating sleeve is in the normal position.

[0005] In another aspect, the disclosure can generally relate to a casing
check valve system for providing isolation within a wellbore. The system
can include a casing string disposed in a wellbore, where the casing
string includes a number of casing pipe. The system can also include an
operational string comprising an operating tool, where the operating tool
includes at least one complementary coupling feature. The system can
further include a casing check valve coupled to a first casing pipe,
where the casing check valve can include a housing and an actuating
sleeve. The housing of the casing check valve can include a housing body
forming a housing cavity that traverses therethrough, where the housing
body includes a top portion, a middle portion, and a bottom portion. The
housing of the casing check valve can also include at least one actuating
sleeve coupling feature disposed on an inner surface of the middle
portion of the housing body. The housing of the casing check valve can
further include a flapper assembly disposed along the inner surface of
the bottom portion of the housing body. The housing of the casing check
valve can also include a flapper seat disposed on the inner surface of
the bottom portion of the housing body adjacent to the flapper assembly.
The housing of the casing check valve can further include a first casing
pipe coupling feature disposed on the top portion of the housing body,
where the first casing pipe coupling feature couples to a first casing
pipe of the casing pipe. The actuating sleeve of the casing check valve
can be disposed within the housing cavity between an actuated position
and a normal position, where the actuating sleeve is concentric with and
adjacent to the housing. The actuating sleeve of the casing check valve
can include an actuating sleeve body forming an actuating sleeve cavity,
inside of which the operational string is disposed. The actuating sleeve
of the casing check valve can also include at least one housing coupling
feature disposed on an outer surface of the actuating sleeve, where the
at least one housing coupling feature is removably coupled to the at
least one actuating sleeve coupling feature of the housing as the
actuating sleeve moves between the actuated position and the normal
position. The actuating sleeve of the casing check valve can further
include at least one operating tool coupling feature that receives the at
least one complementary coupling feature of the operating tool disposed
within the sleeve cavity. The actuating sleeve of the casing check valve
can also include a distal extension that extends from a distal end of the
actuating sleeve body, where the distal extension opens the flapper
assembly when the actuating sleeve is in the actuated position, and where
the distal extension allows the flapper to close when the actuating
sleeve is in the normal position.

[0006] In yet another aspect, the disclosure can generally relate to a
method for isolating a section of a wellbore. The method can include
receiving a coupling feature of an operating tool. The method can also
include repositioning, based on movement of the operating tool in a
direction, an actuating sleeve within a housing body from a first
position to a second position, where repositioning the actuating sleeve
from the first position to the second position changes a flapper assembly
from a first state to a second state. The method can further include
releasing, based on continued movement of the operating tool in the
direction, the coupling feature of the operating tool.

[0007] These and other aspects, objects, features, and embodiments will be
apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The drawings illustrate only example embodiments of methods,
systems, and devices for casing check valves and are therefore not to be
considered limiting of its scope, as casing check valves may admit to
other equally effective embodiments. The elements and features shown in
the drawings are not necessarily to scale, emphasis instead being placed
upon clearly illustrating the principles of the example embodiments.
Additionally, certain dimensions or positionings may be exaggerated to
help visually convey such principles. In the drawings, reference numerals
designate like or corresponding, but not necessarily identical, elements.

[0009] FIG. 1 shows a schematic diagram of a field system in which casing
check valves can be used in a wellbore in accordance with certain example
embodiments.

[0010] FIG. 2 shows a cross-sectional side view of a casing check valve in
a closed position in accordance with certain example embodiments.

[0011] FIG. 3 shows a cross-sectional side view of the casing check valve
of FIG. 2 in an open position in accordance with certain example
embodiments.

[0012] FIG. 4 shows another cross-sectional side view of the casing check
valve of FIG. 3 in an open position in accordance with certain example
embodiments.

[0013] FIG. 5 shows a cross-sectional side view of another casing check
valve in a closed position in accordance with certain example
embodiments.

[0014] FIG. 6 shows a cross-sectional side view of the casing check valve
of FIG. 5 in an open position in accordance with certain example
embodiments.

[0015] FIG. 7 shows another cross-sectional side view of the casing check
valve of FIG. 6 in an open position in accordance with certain example
embodiments.

[0016] FIG. 8 shows a cross-sectional side view of yet another casing
check valve in an open position in accordance with certain example
embodiments.

[0017] FIG. 9 shows a flowchart of a method for isolating a section of a
wellbore using a casing check valve in accordance with certain example
embodiments.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0018] The example embodiments discussed herein are directed to systems,
apparatuses, and methods of casing check valves in a wellbore. While the
example casing check valves shown in the figures and described herein are
directed to use in a wellbore, example casing check valves can also be
used in other applications, aside from a wellbore, in which a casing
string and/or a need for isolating a section of pipe can be used. Thus,
the examples of casing check valves described herein are not limited to
use in a wellbore.

[0019] Further, while some example embodiments described herein use
hydraulic material and a pressurized hydraulic system to operate the
casing check valve, example casing check valves can also be operated
using other types of systems, such as pneumatic systems. Thus, such
example embodiments are not limited to the use of hydraulic material and
pressurized hydraulic systems. A user as described herein may be any
person that is involved with a field operation (including a tripping
operation) in a subterranean wellbore for a field system. Examples of a
user may include, but are not limited to, a roughneck, a company
representative, a drilling engineer, a tool pusher, a service hand, a
field engineer, an electrician, a mechanic, an operator, a consultant, a
contractor, and a manufacturer's representative.

[0020] Any example casing check valves, or portions (e.g., components)
thereof, described herein can be made from a single piece (as from a
mold). When an example casing check valve or portion thereof is made from
a single piece, the single piece can be cut out, bent, stamped, and/or
otherwise shaped to create certain features, elements, or other portions
of a component. Alternatively, an example casing check valve (or portions
thereof) can be made from multiple pieces that are mechanically coupled
to each other. In such a case, the multiple pieces can be mechanically
coupled to each other using one or more of a number of coupling methods,
including but not limited to adhesives, welding, fastening devices,
compression fittings, mating threads, and slotted fittings. One or more
pieces that are mechanically coupled to each other can be coupled to each
other in one or more of a number of ways, including but not limited to
fixedly, hingedly, removably, slidably, and threadably.

[0021] Components and/or features described herein can include elements
that are described as coupling, fastening, securing, or other similar
terms. Such terms are merely meant to distinguish various elements and/or
features within a component or device and are not meant to limit the
capability or function of that particular element and/or feature. For
example, a feature described as a "coupling feature" can couple, secure,
fasten, and/or perform other functions aside from merely coupling. In
addition, each component and/or feature described herein (including each
component of an example casing check valve) can be made of one or more of
a number of suitable materials, including but not limited to metal (e.g.,
stainless steel), ceramic, rubber, and plastic.

[0022] A coupling feature (including a complementary coupling feature) as
described herein can allow one or more components and/or portions of an
example casing check valve (e.g., a sleeve) to become mechanically
coupled, directly or indirectly, to another portion (e.g., a wall) of the
casing check valve. A coupling feature can include, but is not limited
to, a portion of a hinge, an aperture, a recessed area, a protrusion, a
slot, a spring clip, a tab, a detent, and mating threads. One portion of
an example casing check valve can be coupled to another portion of a
casing check valve by the direct use of one or more coupling features.

[0023] In addition, or in the alternative, a portion of an example casing
check valve can be coupled to another portion of the casing check valve
using one or more independent devices that interact with one or more
coupling features disposed on a component of the casing check valve.
Examples of such devices can include, but are not limited to, a pin, a
hinge, a fastening device (e.g., a bolt, a screw, a rivet), and a spring.
One coupling feature described herein can be the same as, or different
than, one or more other coupling features described herein. A
complementary coupling feature as described herein can be a coupling
feature that mechanically couples, directly or indirectly, with another
coupling feature.

[0024] Example embodiments of a casing check valve can isolate at least a
distal portion of a wellbore, including an open hole within the wellbore,
beyond the casing string. The example casing check valve can allow the
drill string (also called a tubing string or operational string,
positioned within the cavity of the casing string) to be tripped above
the example casing check valve with the hydrostatic pressure of the mud
column in the cavity of the casing string above the example casing check
valve to be equal to, greater than (overbalanced), or less than
(underbalanced) the open hole pressure below the example casing check
valve. In certain example embodiments, multiple example casing check
valves can be part of and/or disposed within the casing string to provide
redundancy and/or to isolate various sections of the wellbore that are
cased and/or open hole relative to each other.

[0025] Example embodiments of casing check valves in a wellbore will be
described more fully hereinafter with reference to the accompanying
drawings, in which example embodiments of casing check valves in a
wellbore are shown. Casing check valves in a wellbore may, however, be
embodied in many different forms and should not be construed as limited
to the example embodiments set forth herein. Rather, these example
embodiments are provided so that this disclosure will be thorough and
complete, and will fully convey the scope of casing check valves in a
wellbore to those of ordinary skill in the art. Like, but not necessarily
the same, elements (also sometimes called modules) in the various figures
are denoted by like reference numerals for consistency.

[0026] Terms such as "first," "second," "top," "bottom," "end," "inner,"
"outer," "proximal," and "distal" are used merely to distinguish one
component (or part of a component or state of a component) from another.
Such terms are not meant to denote a preference or a particular
orientation. Also, the names given to various components described herein
are descriptive of one embodiments and are not meant to be limiting in
any way. Those of ordinary skill in the art will appreciate that a
feature and/or component shown and/or described in one embodiment (e.g.,
in a figure) herein can be used in another embodiment (e.g., in any other
figure) herein, even if not expressly shown and/or described in such
other embodiment.

[0027] Further, if a component of a figure is described but not expressly
shown or labeled in that figure, the label used for a corresponding
component in another figure can be inferred to that component.
Conversely, if a component in a figure is labeled but not described, the
description for such component can be substantially the same as the
description for the corresponding component in another figure. The
numbering scheme for the various components in the figures herein is such
that each component is a three digit number and corresponding components
in other figures have the identical last two digits.

[0028] FIG. 1 shows a schematic diagram of a land-based field system 100
in which casing check valves can be used within a subterranean wellbore
in accordance with one or more example embodiments. In one or more
embodiments, one or more of the features shown in FIG. 1 may be omitted,
added, repeated, and/or substituted. Accordingly, embodiments of a field
system should not be considered limited to the specific arrangements of
components shown in FIG. 1.

[0029] Referring now to FIG. 1, the field system 100 in this example
includes a wellbore 120 that is formed by a wall 140 in a subterranean
formation 110 using field equipment 130. The field equipment 130 can be
located above a surface 102, such as ground level for an on-shore
application and the sea floor for an off-shore application, and/or within
the wellbore 120. The point where the wellbore 120 begins at the surface
102 can be called the entry point. The subterranean formation 110 can
include one or more of a number of formation types, including but not
limited to shale, limestone, sandstone, clay, sand, and salt. In certain
embodiments, a subterranean formation 110 can also include one or more
reservoirs in which one or more resources (e.g., oil, gas, water, steam)
can be located. One or more of a number of field operations (e.g.,
drilling, setting casing, extracting downhole resources) can be performed
to reach an objective of a user with respect to the subterranean
formation 110.

[0030] The wellbore 120 can have one or more of a number of segments,
where each segment can have one or more of a number of dimensions.
Examples of such dimensions can include, but are not limited to, size
(e.g., diameter) of the wellbore 120, a curvature of the wellbore 120, a
total vertical depth of the wellbore 120, a measured depth of the
wellbore 120, and a horizontal displacement of the wellbore 120. The
field equipment 130 can be used to create and/or develop (e.g., insert
casing pipe, extract downhole materials) the wellbore 120. The field
equipment 130 can be positioned and/or assembled at the surface 102. The
field equipment 130 can include, but is not limited to, an optional
control unit 109 (including an optional hydraulic operating control line
121, as explained below), a derrick, a tool pusher, a clamp, a tong,
drill pipe, a drill bit, example isolator subs, tubing pipe, a power
source, and casing pipe.

[0031] The field equipment 130 can also include one or more devices that
measure and/or control various aspects (e.g., direction of wellbore 120,
pressure, temperature) of a field operation associated with the wellbore
120. For example, the field equipment 130 can include a wireline tool
that is run through the wellbore 120 to provide detailed information
(e.g., curvature, azimuth, inclination) throughout the wellbore 120. Such
information can be used for one or more of a number of purposes. For
example, such information can dictate the size (e.g., outer diameter) of
casing pipe to be inserted at a certain depth in the wellbore 120.

[0032] Inserted into and disposed within the wellbore are a number of
casing pipe 125 that are coupled to each other to form the casing string
124. In this case, each end of a casing pipe 125 has mating threads
disposed thereon, allowing a casing pipe 125 to be mechanically coupled
to an adjacent casing pipe 125 in an end-to-end configuration. The casing
pipes 125 of the casing string 124 can be mechanically coupled to each
other directly or using a coupling device, such as a coupling sleeve. The
casing string 124 is not disposed in the entire wellbore 120. Often, the
casing string 124 is disposed from approximately the surface 102 to some
other point in the wellbore 120. The open hole portion 127 of the
wellbore 120 extends beyond the casing string 124 at the distal end of
the wellbore 120.

[0033] Each casing pipe 125 of the casing string 124 can have a length and
a width (e.g., outer diameter). The length of a casing pipe 125 can vary.
For example, a common length of a casing pipe 125 is approximately 40
feet. The length of a casing pipe 125 can be longer (e.g., 60 feet) or
shorter (e.g., 10 feet) than 40 feet. The width of a casing pipe 125 can
also vary and can depend on the cross-sectional shape of the casing pipe
125. For example, when the cross-sectional shape of the casing pipe 125
is circular, the width can refer to an outer diameter, an inner diameter,
or some other form of measurement of the casing pipe 125. Examples of a
width in terms of an outer diameter can include, but are not limited to,
7 inches, 75/8 inches, 85/8 inches, 103/4 inches, 133/8 inches, and 14
inches.

[0034] The size (e.g., width, length) of the casing string 124 is
determined based on the information gathered using field equipment 130
with respect to the wellbore 120. The walls of the casing string 124 have
an inner surface that forms a cavity 123 that traverses the length of the
casing string 124. Each casing pipe 125 can be made of one or more of a
number of suitable materials, including but not limited to stainless
steel. In certain example embodiments, the casing pipes 125 are made of
one or more of a number of electrically conductive materials. A cavity
123 can be formed by the walls of the casing string 124.

[0035] The casing check valve 250 can be considered a part of, or separate
from, the casing string 124. In such a case, one or more example casing
check valves 250 can be part of, or disposed within, the casing string
124. A casing check valve 250 can be placed at any location along the
casing string 124. In any case, the top end of the casing check valve 250
can couple to a casing pipe 125. In some cases, as shown in FIG. 8 below,
if the casing check valve 250 is not placed at the end of the casing
string 124, the bottom end of the casing check valve 250 can couple to
another casing pipe 125. In some cases, the portion of the wellbore 120
above the casing check valve 250 (between the casing check valve and the
surface 102) can be called the cased section (or cased hole section) of
the wellbore 120, and the portion of the wellbore 120 below the casing
check valve 250 can be called the open end section of the wellbore 120.
Further details of the casing check valve 250 are provided below with
respect to FIGS. 2-8.

[0036] A number of tubing pipes 115 that are coupled to each other and
inserted inside the cavity 123 form the tubing string 114. The collection
of tubing pipes 115 can be called a tubing string 114. The tubing pipes
115 of the tubing string 114 are mechanically coupled to each other
end-to-end, usually with mating threads. The tubing pipes 115 of the
tubing string 114 can be mechanically coupled to each other directly or
using a coupling device, such as a coupling sleeve or an isolator sub
(both not shown). Each tubing pipe 115 of the tubing string 114 can have
a length and a width (e.g., outer diameter). The length of a tubing pipe
115 can vary. For example, a common length of a tubing pipe 115 is
approximately 30 feet. The length of a tubing pipe 115 can be longer
(e.g., 40 feet) or shorter (e.g., 10 feet) than 30 feet. Also, the length
of a tubing pipe 115 can be the same as, or different than, the length of
an adjacent casing pipe 125.

[0037] The width of a tubing pipe 115 can also vary and can depend on one
or more of a number of factors, including but not limited to the target
depth of the wellbore 120, the total length of the wellbore 120, the
inner diameter of the adjacent casing pipe 125, and the curvature of the
wellbore 120. The width of a tubing pipe 115 can refer to an outer
diameter, an inner diameter, or some other form of measurement of the
tubing pipe 115. Examples of a width in terms of an outer diameter for a
tubing pipe 115 can include, but are not limited to, 7 inches, 5 inches,
and 4 inches.

[0038] In some cases, the outer diameter of the tubing pipe 115 can be
such that a gap exists between the tubing pipe 115 and an adjacent casing
pipe 125. The walls of the tubing pipe 115 have an inner surface that
forms a cavity that traverses the length of the tubing pipe 115. The
tubing pipe 115 can be made of one or more of a number of suitable
materials, including but not limited to steel.

[0039] At the distal end of the tubing string 114 within the wellbore 120
is a bottom hole assembly (sometimes referred to herein as a "BHA") 101.
The BHA 101 can include a drill bit 108 at the far distal end. The drill
bit 108 is used to extend the open hole portion 127 of the wellbore 120
in the formation 110 by cutting into the formation 110. The BHA 101 can
also include one or more other components, including but not limited to
an operating tool 107, one or more tubing pipes 115, a
measurement-while-drilling tool, and a wrench flat. During a field
operation that involves drilling (extending the open hole portion 127 of
the wellbore 120), the tubing string 114, including the BHA 101, can be
rotated by other field equipment 130.

[0040] In certain example embodiments, the operating tool 107 is included
in the BHA 101. In such a case, the operating tool 107 can be considered
a part of, or separate from, the tubing string 114. In some cases, the
operating tool 107 is positioned away from the BHA 101, closer to the
surface 102. In such a case, the operating tool 107 can be considered
part of the tubing string 114. One or more example operating tools 107
can be part of, or disposed within, the tubing string 114. An operating
tool 107 can be placed at any location along the tubing string 114. In
any case, the top end of the operating tool 107 can couple to a tubing
pipe 115. In addition, the bottom end of the operating tool 107 can
couple to another tubing pipe 115 or some portion of the BHA 101. Further
details of the operating tool 107 are provided below with respect to FIG.
2.

[0041] The optional control unit 109 can include one or more components
that allow a user to control one or more components of the casing check
valve 250 (e.g., a housing coupling feature of the actuating sleeve)
and/or one or more components (e.g., a complementary coupling feature of
an operating tool) that interact with the casing check valve 250 from the
surface 102. Examples of such components of the control unit 109 can
include, but are not limited to, a compressor, one or more valves, a
pump, piping, and a computer. The hydraulic operating control line 121
can be disposed between the casing string 124 and the wall 140 of the
wellbore 120 and/or within the casing string 124.

[0042] FIG. 1 shows a field operation that involves drilling. Those of
ordinary skill in the art will appreciate that other field operations can
be conducted in the setting of FIG. 1. For example, a field operation can
be a wireline or similar type of logging operation. In such a case, one
or more of the components of FIG. 1 can be altered to account for the
field operation. For example, a wireline 114 (as an example) can replace
the tubing string, and a wireline tool 101 (or, more generally, a logging
tool 101) can replace the BHA. In such a case, an operating tool 107 can
be part of the wireline 114 and allow the wireline tool 101 to pass
beyond the casing check valve 250 and take measurements in the open hole
portion 127 of the wellbore 120 by opening the flapper assembly using the
distal extension of the actuating sleeve, all as described below. In
light of this flexibility between field operations, the tubing string 114
can more generally be called an operational string 114.

[0043] FIG. 2 shows a cross-sectional side view of a subsystem 201 that
includes a casing check valve 250 in a normal position in accordance with
certain example embodiments. In one or more embodiments, one or more of
the features shown in FIG. 2 may be omitted, added, repeated, and/or
substituted. Accordingly, embodiments of a casing check valve should not
be considered limited to the specific arrangements of components shown in
FIG. 2. For example, while the flapper seat 239 is shown and described
below as being part of the bottom portion 234 of the housing body 256,
the flapper seat 239 could be part of the middle portion 233 of the
housing body 256.

[0044] Referring to FIGS. 1 and 2, the casing check valve 250 can have a
housing 298 and an actuating sleeve 260. In certain example embodiments,
the housing 298 includes a housing body 256. The housing body 256 can
have multiple portions. For example, as shown in FIG. 2, the housing body
256 can have a top portion 232 (also called a top end 232), a middle
portion 233 (also called a middle section 233), and a bottom portion 234
(also called a bottom end 234). The various portions of the housing body
256 of the casing check valve 250 can be made from a single piece or
multiple pieces. The housing body 256 can have a height 292 and a width
280. Each portion of the housing body 256 can have a common outer surface
251. A cavity 289 disposed inside of the housing body 256 can traverse
the height 292 of the housing body 256. The cavity 289 can be the same
as, or different than, the cavity 123 of the casing string 124.

[0045] The top end 232 of the housing body 256 of FIG. 2 can have an inner
surface 252, a top surface 254, the outer surface 251, and a bottom
surface 278. In certain example embodiments, the housing body 256 can
also include coupling features 299 disposed on and/or between the inner
surface 252 and/or the top surface 254. In such a case, the coupling
features 299 (e.g., mating threads) can be used to couple to an adjacent
casing pipe 125. The inner surface 252 can form the cavity 289 that
traverses the height 275 of the top end 232. The inner surface 252 of the
top portion 232, when viewed cross-sectionally from above, can have one
or more of a number of shapes. Examples of such shapes can include, but
are not limited to, a circle, an oval, a square, and a hexagon.

[0046] In certain example embodiments, the cross-sectional shape formed by
the inner surface 252 of the top end 232 can be substantially the same as
the cross-sectional shape formed by the inner surface of an adjacent
casing pipe 125. Similarly, the size (e.g., perimeter) of the
cross-sectional area formed by the inner surface 252 of the top portion
232 can be substantially the same as the size of the cross-sectional area
formed by the inner surface of a casing pipe 125. In this case, the
cross-sectional shape formed by the inner surface 252 is a circle having
a diameter 242. Likewise, the size and shape of the cross-section formed
by the outer surface 251 of the top end 232 can be substantially the same
as the size and shape of the cross-section formed by the outer surface of
a casing pipe 125.

[0047] The bottom end 234 of the housing body 256 of FIG. 2 can have an
inner surface 287, a top surface (in this case, designated by the flapper
seat 239), the outer surface 251, a bottom surface 255, a flapper
assembly 286, and a recessed area 280 disposed within a portion of the
inner surface 287 adjacent to the flapper assembly 286. The inner surface
287 can form the cavity 289 that traverses the height 235 of the bottom
end 234. The inner surface 287 of the bottom end 234, when viewed
cross-sectionally from above, can have one or more of a number of shapes.
Examples of such shapes can include, but are not limited to, a circle, an
oval, a square, and a hexagon. The cross-sectional shape formed by the
inner surface 287 of the bottom end 234 can be substantially the same as
the cross-sectional shape formed by the inner surface 252 of the top end
232. Thus, in this case, the cross-sectional shape formed by the inner
surface 287 can be a circle.

[0048] In certain example embodiments, the cross-sectional shape formed by
the inner surface 287 of the bottom end 234 can be substantially the same
as the cross-sectional shape formed by the inner surface of a casing pipe
125. Similarly, as shown in FIG. 8 below, the size (e.g., perimeter) of
the cross-sectional area formed by the inner surface 287 of the bottom
end 234 can be substantially the same as the size of the cross-sectional
area formed by the inner surface 252 of the top end 232 and/or the inner
surface of a casing pipe 125.

[0049] Alternatively, as shown in FIG. 2, the size of the cross-sectional
area formed by the inner surface 287 of the bottom end 234 can be
different than the size of the cross-sectional area formed by the inner
surface 252 of the top end 232 and/or the inner surface of a casing pipe
125. In this example, the inner surface 287 of the bottom end 234 has a
diameter 243 that is larger than the diameter 242 of the inner surface
252 of the top end 232 and the inner surface of the casing pipe 125.
Similarly, the size and shape of the cross-section formed by the outer
surface 251 of the bottom end 234 can be substantially the same as, or
different than, the size and shape of the cross-section formed by the
outer surface 251 of the top end 232 and/or the outer surface of a casing
pipe 125.

[0050] As described below with respect to FIG. 8, one or more optional
coupling features (e.g., mating threads) can be disposed on or between
the inner surface 287 and the bottom surface 255 of the bottom end 234,
where these coupling features can be used to mechanically couple the
casing check valve 250 to an adjacent casing pipe 125 in the casing
string 124. In the example shown in FIG. 2, there are no coupling
features disposed on the bottom portion 234 because the casing check
valve is disposed at the end of the casing string 124.

[0051] In certain example embodiments, the flapper seat 239 is one or more
protrusions that extend inward by a distance 270 from the inner surface
287 of the bottom end 234, into the cavity 289. The purpose of the
flapper seat 239 is to prevent the flapper 271 of the flapper assembly
286 (discussed below) from traveling beyond a certain point toward the
middle section 233 of the housing body 256. The flapper seat 239 can be
one or more discrete protrusions that extend inward from the inner
surface 287 of the bottom end 234. Alternatively, the flapper seat 239
can be a single protrusion that is continuous around the inner surface
287 of the bottom end 234. The distance 285 within the cavity 289 defined
by the flapper seat 239 can be less than the length of the flapper 271.
In addition, the distance 285 can be at least as great as the inner
diameter 242 of the casing pipe 125. The flapper seat 239 can have a
thickness 284.

[0052] In certain example embodiments, the flapper assembly 286 includes a
flapper 271 and a hinge 272 and is disposed, at least in part, along the
inner surface 287 of the bottom portion 234. The hinge 272 can be
disposed within or adjacent to the housing body 256. The hinge 272 can be
used to move the flapper 271 between a closed position (e.g., when the
flapper 271 abuts against the flapper seat 239) and an open position
(e.g., when the flapper 271 is positioned in the recessed area 280
(discussed below). When in the closed position, the flapper 271 can
create a seal against the flapper seat 239, preventing substantially any
material (e.g., fluids, gases) from traveling within the cavity 289
between the bottom portion 234 and the middle portion 233. The flapper
271 can have a thickness 277.

[0053] The closed position of the flapper 271 can be the default position
of the flapper 271. In other words, the hinge 272 can operate on a
mechanical (e.g., a spring), hydraulic, or other basis to put the flapper
271 in the default (in this case, the closed) position. The force that
the hinge 272 applies to the flapper 271 in the closed position can be
overcome by a greater force, such as the force applied by the distal
extension 264 of the actuating sleeve 260 (described below) on the
flapper 271 when the actuating sleeve 260 is moved toward an actuated
position. For example, as shown in FIG. 3, when the actuating sleeve 260
is moved toward the actuating sleeve, the distal extension 264 forces the
flapper 271 to move from the closed position to the open position.

[0054] The recessed area 280 has a height 294 and a width 245 that is at
least as great as the height and the width of the flapper 271. In this
way, when the flapper 271 is in the open position, the flapper fits
entirely within the recessed area 280 and does not protrude beyond the
inner wall 287 toward the cavity 289. As a result, the housing body 256
has a thickness 231 that is less than the thickness 246 of the rest of
the housing body 256 in the bottom portion 234. The recessed area 280 can
be disposed along a portion (as shown in FIG. 2) or all of the perimeter
of the inner surface of the bottom portion 234. The recessed area 280 can
be defined, at least in part, by the inner surface 290 and the bottom
surface 291. The remainder of the bottom portion 234 adjacent to (below)
the recessed area 280 can have a height 276.

[0055] In certain example embodiments, the middle section 233 of the
housing body 256 is disposed between the top end 232 and the bottom end
234. The middle section 233 can include the outer surface 251, the inner
surface 287, and at least one actuating sleeve coupling feature (e.g.,
actuating sleeve coupling feature 254, actuating sleeve coupling feature
257). The inner surface 287 can form the cavity 289 that traverses the
height 261 of the middle portion 233. The inner surface 287 of the middle
portion 233, when viewed cross-sectionally from above, can have one or
more of a number of shapes. Examples of such shapes can include, but are
not limited to, a circle, an oval, a square, and a hexagon. The
cross-sectional shape formed by the inner surface 287 of the middle
portion 233 can be substantially the same as the cross-sectional shape
formed by at least a portion of the inner surface 287 of the bottom end
232. Thus, in this case, the cross-sectional shape formed by the inner
surface 287 can be a circle.

[0056] Similarly, as shown in FIG. 8 below, the size (e.g., perimeter) of
the cross-sectional area formed by the inner surface 287 of the middle
portion 233 can be substantially the same as the size of the
cross-sectional area formed by the inner surface 287 of at least a
portion of the bottom end 234. In addition, the size and shape of the
cross-section formed by the outer surface 251 of the middle portion 233
can be substantially the same as, or different than, the size and shape
of the cross-section formed by the outer surface 287 of the bottom end
234 and/or the outer surface of a casing pipe 125.

[0057] In certain example embodiments, an actuating sleeve coupling
feature (e.g., actuating sleeve coupling feature 254, actuating sleeve
coupling feature 257) can be disposed on the inner surface 287 of the
middle portion 233 of the housing body 256. Each actuating sleeve
coupling feature of the housing body 256 can have a shape, size, and
features that allow it to become removably coupled to a housing coupling
feature 263 of the actuating sleeve 260, as described below. For example,
as shown in FIG. 2, the actuating sleeve coupling feature 254 and the
actuating sleeve coupling feature 257 each form a recess into the housing
body 256 from the inner surface 287. Specifically, the actuating sleeve
coupling feature 254 and the actuating sleeve coupling feature 257 each
have a back surface 237 that is adjacent to angled side surface 236 on
one side and angled side surface 238 on the other side.

[0058] Angled side surface 236 and angled side surface 238 end at the
inner surface 287 of the middle portion 233. Further, the angle between
the angled side surface 236 and the back surface 237, as well as the
angle between the angled side surface 238 and the back surface 237, can
be obtuse to allow for movement of the housing coupling feature 263 from
one actuating sleeve coupling feature (e.g., actuating sleeve coupling
feature 254) to another actuating sleeve coupling feature (e.g.,
actuating sleeve coupling feature 257) without decoupling the operating
tool coupling feature 266 of the actuating sleeve 260 and the
complementary coupling feature 106 of the operating tool 107, as
described below.

[0059] In certain example embodiments, there can be one or more stops
disposed on an inner surface of the housing body 256. The stops can be
used to limit the travel of the actuating sleeve 260 within the cavity
289. For example, the bottom surface 278 of the top portion 232 can serve
as a stop. In such a case, the bottom surface 278 of the top portion 232
can act as a stop to position the actuating sleeve 260 in a normal
position. As another example, the flapper seat 239 can serve as a stop.
In such a case, the flapper seat 239 can act as a stop to position the
actuating sleeve 260 in an actuated position.

[0060] The positioning of the stops can coincide with the positioning of
the actuating sleeve coupling features. For example, the actuating sleeve
coupling feature 257 can be located a distance 295 from the actuating
sleeve coupling feature 254, which can coincide with when the top surface
268 of the actuating sleeve 260 abuts against the bottom surface 278 of
the housing body 256 and when the bottom surface 258 of the actuating
sleeve 260 abuts against the flapper seat 239 of the housing 298,
respectively.

[0061] The top portion 232 and/or the bottom portion 234 of the housing
body 256 can be merged with (e.g., form a single piece with) the middle
portion 233. Alternatively, one or more of the top portion 232, the
middle portion 233, and the bottom portion 234 of the housing body 256
can be a separate piece that is coupled to one or more other portions of
the housing body 256 using one or more coupling features. For example,
the middle portion 233 can be coupled to the top portion 232 and the
bottom portion 234 using a coupling feature (e.g., mating threads). The
middle portion 233 can be disposed at any point along the height 292 of
the housing body 256 relative to the top portion 232 and the bottom
portion 234.

[0062] In certain example embodiments, the actuating sleeve 260 is movably
disposed within the cavity 289 formed by the housing body 256. For
example, as shown in FIG. 2, at least a portion of the actuating sleeve
260 is disposed adjacent to the middle portion 233 of the housing body
256. The actuating sleeve 260 can include one or more of a number of
components. For example, as shown in FIG. 2, the actuating sleeve 260 can
include an actuating sleeve body 240, at least one housing coupling
feature 263, at least one operating tool coupling feature 266, and a
distal extension 260. The various portions of the actuating sleeve 260
can be made from a single piece or multiple pieces.

[0063] In certain example embodiments, the actuating sleeve body 240 has
an inner surface 267, a top surface 268, an outer surface 204, and a
bottom surface 258. The actuating sleeve body 240 can have a height 249,
a width 244 (defined by the outer surface 204), and a width 242 of the
cavity 222 (defined by the inner surface 267). A cavity 222 disposed
inside of the actuating sleeve body 240 can traverse the height 249 of
the actuating sleeve body 240. The cavity 222 can be a subset of the
cavity 289 of the housing body 256. The cavity 222 can also be disposed
within the distal extension 260 of the actuating sleeve 260. The inner
surface 267 of the actuating sleeve body 240, when viewed
cross-sectionally from above, can have one or more of a number of shapes.
Examples of such shapes can include, but are not limited to, a circle, an
oval, a square, and a hexagon.

[0064] In certain example embodiments, the cross-sectional shape formed by
the inner surface 267 of the actuating sleeve body 240 can be
substantially the same as the cross-sectional shape formed by the inner
surface 287 of the middle portion 233 of the housing body 256. Similarly,
the size (e.g., perimeter, diameter 244) of the cross-sectional area
formed by the outer surface 204 of the actuating sleeve body 240 can be
less than the size (e.g., perimeter, diameter 243) of the cross-sectional
area formed by the inner surface 287 of the middle portion 233 of the
housing body 256. In such a case, the actuating sleeve 260 can move
(e.g., slide) within the cavity 289 formed by the middle portion 233 of
the housing body 256.

[0065] Each housing coupling feature 263 of the actuating sleeve 260 is
disposed on the outer surface 204 of the actuating sleeve body 240. The
housing coupling feature 263 can extend outward from the outer surface
204. In certain example embodiments, the housing coupling feature 263 is
retractable (e.g., can move inward and outward, perpendicular with
respect to the outer surface 204). In such a case, the normal position of
the housing coupling feature 263 can be outward, as shown in FIG. 2,
where the housing coupling features 263 are disposed within the recess
formed by the actuating sleeve coupling feature 257. The normal position
of the housing coupling features 263 can be maintained by one or more
components, including but not limited to one or more springs mounted
within the actuating sleeve body 240. Alternatively, the housing coupling
features 263 can be made of a semi-flexible material that reverts to its
normal state when insufficient forces are applied to move it to a
retracted state.

[0066] As the actuating sleeve 240 moves from a normal position (in this
case, corresponding to when the housing coupling features 263 are coupled
to (e.g., disposed within) the actuating sleeve coupling feature 257) to
an actuated position (in this case, corresponding to when the housing
coupling features 263 are coupled to (e.g., disposed within) the
actuating sleeve coupling feature 254), the housing coupling features 263
are pressed inward by the inner surface 287 of the middle portion 233 of
the housing body 256. When the actuating sleeve 240 is in the normal
position or the actuated position, the housing coupling features 263 are
extended (in their normal position). In certain example embodiments, each
housing coupling feature 263 is a collet.

[0067] As discussed above, the housing coupling features 263 can have one
or more features that complement the features of the actuating sleeve
coupling features of the housing body 256. In this example, each housing
coupling feature 263 can have a front surface 228 that is adjacent to
angled side surface 227 on one side and angled side surface 229 on the
other side. The angle between the angled side surface 227 and the front
surface 228, as well as the angle between the angled side surface 229 and
the front surface 228, can be obtuse to allow for retraction of the
housing coupling feature 263, allowing the actuating sleeve 260 to move
from one actuating sleeve coupling feature (e.g., actuating sleeve
coupling feature 254) to another actuating sleeve coupling feature (e.g.,
actuating sleeve coupling feature 257). Again, the retractability of the
housing coupling features 263 help allow for movement of the actuating
sleeve 260 without decoupling the operating tool coupling feature 266 of
the actuating sleeve 260 and the complementary coupling feature 106 of
the operating tool 107, as described below.

[0068] In certain example embodiments, one or more operating tool coupling
features (e.g., operating tool coupling feature 266) can be disposed on
the inner surface 267 of the actuating sleeve body 240. Each operating
tool coupling feature 266 of the actuating sleeve body 240 can have a
shape, size, and features that allow it to become removably coupled to a
complementary coupling feature 106 of the operating tool 107, as
described below. For example, as shown in FIG. 2, the operating tool
coupling feature 266 can form a recess into the actuating sleeve body 240
from the inner surface 267. Specifically, the operating tool coupling
feature 266 can have a back surface 282 that is adjacent to angled side
surface 281 on one side and angled side surface 283 on the other side.

[0069] Angled side surface 281 and angled side surface 283 end at the
inner surface 267 of the actuator sleeve body 240. Further, the angle
between the angled side surface 281 and the back surface 282, as well as
the angle between the angled side surface 283 and the back surface 282,
can be obtuse to allow for movement of the complementary coupling feature
106 when the actuating sleeve 260 has reached its normal position or its
actuated position relative to the housing body 256.

[0070] In certain example embodiments, the distal extension 264 of the
actuating sleeve 260 extends from a distal end (in this case, from bottom
surface 258) of the actuating sleeve body 240. The distal extension 264
can be defined by the inner surface 267, a bottom surface 269, and an
outer surface 261. The thickness of the distal extension 264 can be
defined by the diameter 279 of the outer surface 261 less the diameter
242 of the inner surface 267. Alternatively, the thickness of the distal
extension 264 can be defined by the diameter 244 of the outer surface 204
of the actuating sleeve body 240 less the length 259 of the bottom
surface 269 of the actuating sleeve body 240. The diameter 279 of the
outer surface 261 of the distal extension 264 can be less than the
distance 285 within the cavity 289 defined by the flapper seat 239.

[0071] As shown in FIG. 2, when the actuating sleeve 260 is in the normal
position, the distal extension 264 is positioned within the cavity 289
defined by the middle portion 233 of the housing body 256. In such a
case, the distal extension 264 does not contact the flapper 271 of the
flapper assembly 286, where the flapper 271 is in the closed position by
abutting against the flapper seat 239. As the actuating sleeve 260 moves
from the normal position to the actuated position, as shown in FIG. 3
below, the distal extension 264 contacts the flapper 271 and applies
enough downward force to the flapper 271 to overcome the opposing force
of the hinge 272, forcing the flapper into the open position.

[0072] In certain example embodiments, the operating tool 107 disposed
within the tubing string 114 (and, more specifically, to a tubing pipe
115) has one or more complementary coupling features 106. Each
complementary coupling feature 106 of the operating tool 107 is disposed
on the outer surface of the operating tool 107. The complementary
coupling feature 106 can extend outward from the outer surface of the
operating tool 107. In certain example embodiments, the complementary
coupling feature 106 is retractable (e.g., can move inward and outward,
perpendicular with respect to the outer surface). In such a case, the
normal position of the complementary coupling feature 106 can be outward,
as shown in FIG. 2, where the complementary coupling features 106 are
disposed within the recess formed by the operating tool coupling feature
266. The normal position of the complementary coupling features 106 can
be maintained by one or more components, including but not limited to one
or more springs mounted within the operating tool 107. Alternatively, the
complementary coupling features 106 can be made of a semi-flexible
material that reverts to its normal state when insufficient forces are
applied to move it to a retracted state.

[0073] As yet another alternative, the complementary coupling features 106
can operate using hydraulic control. In such a case, the control unit
109, using the hydraulic operating control line 121, can apply a
hydraulic pressure to a hydraulic material to maintain the complementary
coupling features 106 in an extended position and remove the hydraulic
pressure to allow the complementary coupling features 106 to move to a
retracted position. In certain example embodiments, the hydraulic
material can be a liquid (fluid), a gas (in which case, the hydraulic
material can also be called a pneumatic material), or have any other
suitable state. A non-limiting example of a hydraulic material is oil.

[0074] The movement of the operating tool 107 (and, thus, the tubing
string 114) moves vertically within the cavity 222 of the actuating
sleeve body 240, the actuating sleeve 240 moves between the normal
position (in this case, corresponding to when the housing coupling
features 263 are coupled to (e.g., disposed within) the actuating sleeve
coupling feature 257) and the actuated position (in this case,
corresponding to when the housing coupling features 263 are coupled to
(e.g., disposed within) the actuating sleeve coupling feature 254). Once
the actuating sleeve 240 reaches either of these positions relative to
the housing body 256, as the operating tool 107 continues to move in the
same direction, the force applied to the tubing string 114 overcomes the
coupling force (either by the configuration of these coupling features or
by some other factor, such as hydraulic control) between the
complementary coupling features 106 of the operating tool 107 and the
operating tool coupling features 266 of the actuating sleeve 260. In
certain example embodiments, the complementary coupling features 106 of
the operating tool 107 is called a dog.

[0075] As discussed above, the complementary coupling features 106 can
have one or more features that complement the features of the operating
tool coupling features 266 of the actuating sleeve 260. In this example,
each complementary coupling feature 106 can have a front surface 113 that
is adjacent to angled side surface 112 on one side and angled side
surface 116 on the other side. There can also be a side surface 111 that
extends from the outer surface of the operating tool 107 and joins with
the angled side 112, as well as another side surface 117 that extends
from the outer surface of the operating tool 107 and joins with the
angled side 116. The angle between the angled side surface 112 and the
front surface 113, as well as the angle between the angled side surface
116 and the front surface 113, can be obtuse to allow for retraction of
the complementary coupling feature 106, allowing the operating tool 107
(and, thus, the tubing string 114) to move beyond the casing check valve
250.

[0076] For example, if a tripping operation of the tubing string 114 were
occurring, where the tubing string 114 is being drawn to the surface 102,
when the housing coupling feature 263 of the actuating sleeve 260 is
coupled to the actuating sleeve coupling feature 257 of the housing body
256, putting the actuating sleeve 260 in the normal position, then the
top surface 268 of the actuating sleeve 260 abuts against the bottom
surface 278 of the housing body 256. When this occurs, the actuating
sleeve 260 cannot move further toward the surface 102. In other words,
the furthest length of proximal travel for the actuating sleeve 260
within the cavity 289 formed by the middle portion 233 of the housing
body 256 can be when the actuating sleeve 260 is in the normal position.
As a result, this holding force by the housing body 256 on the actuating
sleeve 260, as the tubing string 114 moves toward the surface 102, is
strong enough to overcome the force that couples the operating tool
coupling features 266 of the actuating sleeve 260 with the complementary
coupling features 106 of the operating tool 107. Consequently, the tubing
string 114, including the operating tool 107, can be lifted up through
the cavity 123 of the casing string 124, away from the casing check valve
250.

[0077] FIGS. 3 and 4 show a subsystem cross-sectional side view of the
casing check valve of FIG. 2 in an open position in accordance with
certain example embodiments. In one or more embodiments, one or more of
the features shown in FIGS. 3 and 4 may be omitted, added, repeated,
and/or substituted. Accordingly, embodiments of a casing check valve
should not be considered limited to the specific arrangements of
components shown in FIGS. 3 and 4.

[0078] The components in the subsystem 301 of FIG. 3 and the subsystem 401
of FIG. 4 are substantially similar to the corresponding components in
the subsystem 201 of FIG. 2, except as described below. Referring to
FIGS. 1-4, the casing check valve 350 (and, more specifically, the
actuating sleeve 260) of the subsystem 301 of FIG. 3 and the casing check
valve 450 of the subsystem 401 of FIG. 4 are shown in the actuated
position. In FIG. 3, the tubing string 114 is inserted further into the
wellbore 120 toward the open hole portion 127 to extend the wellbore 120.
In the subsystem 301 of FIG. 3, the complementary coupling features 106
of the operating tool 107 are engaged with (coupled to) the operating
tool coupling features 266 of the actuating sleeve 260.

[0079] As the tubing string 114 (and, more specifically, the operating
tool 107) is moved downward in the wellbore 120, the actuating sleeve 260
moves with respect to the housing body 256 from the normal position (as
shown in FIG. 2) to the actuated position (as shown in FIG. 3).
Specifically, in the actuated position of FIG. 3, the housing coupling
feature 263 of the actuator sleeve 260 are coupled to (e.g., disposed
within) the actuating sleeve coupling feature 254 of the housing body
256.

[0080] As described above, when the actuating sleeve 260 is in the normal
position, the distal extension 264 is positioned within the cavity 289
defined by the middle portion 233 of the housing body 256. In such a
case, the distal extension 264 does not contact the flapper 271 of the
flapper assembly 286, where the flapper 271 is in the closed position by
abutting against the flapper seat 239. As the actuating sleeve 260 moves
from the normal position (as shown in FIG. 2, putting the casing check
valve 250 in the closed position) to the actuated position, as shown in
FIG. 3, the distal extension 264 contacts the flapper 271 and applies
enough downward force to the flapper 271 to overcome the opposing force
of the hinge 272, forcing the flapper into the open position. In other
words, the flapper 271 is forced into and held within the recessed area
280 when the actuating sleeve 260 is in the actuated position with
respect to the housing body 256. When the actuating sleeve 260 is in the
actuated position, the casing check valve 350 is in the open position.

[0081] In FIG. 4, the tubing string 114 is inserted even further (relative
to FIG. 3) into the wellbore 120 toward the open hole portion 127 to
extend the wellbore 120. In the subsystem 401 of FIG. 4, the
complementary coupling features 106 of the operating tool 107 become
engaged from (are decoupled from) the operating tool coupling features
266 of the actuating sleeve 260. Specifically, when the housing coupling
feature 263 of the actuating sleeve 260 is coupled to the actuating
sleeve coupling feature 254 of the housing body 256, putting the
actuating sleeve 260 in the actuated position, then the bottom surface
258 of the actuating sleeve 260 abuts against the flapper seat 239 of the
housing 298.

[0082] When this occurs, the actuating sleeve 260 cannot move further
toward the open hole portion 127 of the wellbore 120. In other words, the
furthest length of distal travel for the actuating sleeve 260 within the
cavity 289 formed by the middle portion 233 of the housing body 256 can
be when the actuating sleeve 260 is in the actuated position. As a
result, this holding force by the housing body 256 on the actuating
sleeve 260, as the tubing string 114 moves toward the open hole portion
127 of the wellbore 120, is strong enough to overcome the force that
couples the operating tool coupling features 266 of the actuating sleeve
260 with the complementary coupling features 106 of the operating tool
107. Consequently, the tubing string 114, including the operating tool
107, can be inserted through the cavity 123 of the casing string 124,
away from the casing check valve 250.

[0083] FIGS. 5-7 show a cross-sectional side view of another casing check
valve 550 in a closed position in accordance with certain example
embodiments. In one or more embodiments, one or more of the features
shown in FIGS. 5-7 may be omitted, added, repeated, and/or substituted.
Accordingly, embodiments of a casing check valve should not be considered
limited to the specific arrangements of components shown in FIGS. 5-7.

[0084] The components in the subsystem 501 of FIG. 5 are substantially
similar to the corresponding components in the subsystem 201 of FIG. 2,
except as described below. Referring to FIGS. 1-7, the casing check valve
550 of the subsystem 501 of FIG. 5 is shown in the closed position as a
result of the actuating sleeve 560 being in the normal position with
respect to the housing body 556. With the casing check valve 550 of FIG.
5, the housing coupling feature 563 of the actuating sleeve 560, as well
as the actuating sleeve coupling feature 557 of the housing body 556 have
different configurations. Specifically, in this case, the housing
coupling feature 563 and the actuating sleeve coupling feature 557 are
mating threads that complement each other.

[0085] Because of the length of the mating threads disposed on the inner
surface 587 of the housing body 556 in FIG. 5, there are not multiple
actuating sleeve coupling features, as with the casing check valve 250 of
FIG. 2. Alternatively, there can be multiple sets of mating threads
(where each set of mating threads represents a actuating sleeve coupling
feature) disposed on the inner surface 587 of the housing body 556. The
actuating sleeve 560 can move between the normal position (putting the
casing check valve 550 in the closed position) and the actuated position
(putting the casing check valve 550 in the open position) by rotating
relative to the housing body 556.

[0086] This rotation of the actuating sleeve 560 can be caused by the
rotation of the tubing string 114 (which includes the operating tool
107). During a field operation, the tubing string 114 is rotated in one
direction (e.g., clockwise) when tubing pipes 115 are being added to the
tubing string 114 (as during drilling), and the tubing string 114 is
rotated in the opposite direction (e.g., counter-clockwise) when tubing
pipes 115 are being removed from the tubing string 114 (as during a
tripping run). When the complementary coupling features 106 of the
operating tool 107 are engaged with (coupled to) the operating tool
coupling features 566 of the actuating sleeve 560, the actuating sleeve
560 rotates along with the operating tool 107.

[0087] As the tubing string 114 is removed from the wellbore, pulling the
operating tool 107 upward, the rotation of the operating tool 107 moves
the actuating sleeve 560 to the normal position, putting the casing check
valve 550 in the closed position. When the top surface 568 of the
actuating sleeve 560 abuts against the bottom surface 578 of the housing
body 556, the actuating sleeve 560 cannot move further toward the surface
102. In other words, the furthest length of proximal travel for the
actuating sleeve 560 within the cavity 589 formed by the middle portion
533 of the housing body 556 can be when the actuating sleeve 560 is in
the normal position. As a result, this holding force by the housing body
556 on the actuating sleeve 560, as the tubing string 114 moves toward
the surface 102, is strong enough to overcome the force that couples the
operating tool coupling features 566 of the actuating sleeve 560 with the
complementary coupling features 106 of the operating tool 107.
Consequently, the tubing string 114, including the operating tool 107,
can be lifted up through the cavity 123 of the casing string 124, away
from the casing check valve 550.

[0088] In the subsystem 601 of FIG. 6, the tubing string 114 is inserted
further into the wellbore 120 toward the open hole portion 127 to extend
the wellbore 120. Relative to the subsystem 501 of FIG. 5, the
complementary coupling features 106 of the operating tool 107 continue to
be engaged with (coupled to) the operating tool coupling features 566 of
the actuating sleeve 560, but the operating tool 107 (along with the rest
of the tubing string 114) is rotating in the opposite direction. As the
tubing string 114 (and, more specifically, the operating tool 107) is
moved downward in the wellbore 120, the actuating sleeve 560 rotates
downward with respect to the housing body 556 from the normal position
(as shown in FIG. 5) to the actuated position (as shown in FIG. 6).

[0089] As described above, when the actuating sleeve 560 is in the normal
position, the distal extension 564 is positioned within the cavity 589
defined by the middle portion 533 of the housing body 556. In such a
case, the distal extension 564 does not contact the flapper 571 of the
flapper assembly 586, where the flapper 571 is in the closed position by
abutting against the flapper seat 539. As the actuating sleeve 560 moves
from the normal position (as shown in FIG. 5, putting the casing check
valve 550 in the closed position) to the actuated position, as shown in
FIG. 6, the distal extension 564 contacts the flapper 571 and applies
enough downward force to the flapper 571 to overcome the opposing force
of the hinge 572, forcing the flapper 571 into the open position. In
other words, the flapper 571 is forced into and held within the recessed
area 580 when the actuating sleeve 560 is in the actuated position with
respect to the housing body 556. When the actuating sleeve 560 is in the
actuated position, the casing check valve 650 is in the open position.

[0090] As the actuating sleeve 560 continues to rotate downward relative
to the housing body 556 using the housing coupling feature 563 and the
actuating sleeve coupling feature 557, the bottom surface 558 of the
actuating sleeve 560 eventually abuts against the flapper seat 539 of the
housing body 556. When this occurs, as shown in FIG. 6, the actuating
sleeve 560 cannot move further toward the open hole portion 127 of the
wellbore 120. In other words, the furthest length of distal travel for
the actuating sleeve 560 within the cavity 589 formed by the middle
portion 533 of the housing body 556 can be when the actuating sleeve 560
is in the actuated position, putting the casing check valve 650 in the
open position.

[0091] If the tubing string 114 continues to rotate, moving the operating
tool 107 further into the open hole portion 127 of the wellbore 120, the
holding force by the housing body 556 on the actuating sleeve 560 (e.g.,
where the bottom surface 558 of the actuating sleeve 560 abuts against
the flapper seat 539 of the housing body 556) is strong enough to
overcome the force that couples the operating tool coupling features 566
of the actuating sleeve 560 with the complementary coupling features 106
of the operating tool 107. Consequently, as shown in FIG. 7, the tubing
string 114, including the operating tool 107, can be inserted through the
cavity 123 of the casing string 124, away from the casing check valve
750.

[0092] FIG. 8 shows a cross-sectional side view of a subsystem 801 that
includes yet another casing check valve 850 in an open position in
accordance with certain example embodiments. In one or more embodiments,
one or more of the features shown in FIG. 8 may be omitted, added,
repeated, and/or substituted. Accordingly, embodiments of a casing check
valve should not be considered limited to the specific arrangements of
components shown in FIG. 8.

[0093] The components in the subsystem 801 of FIG. 8 are substantially
similar to the corresponding components in the subsystem 201 of FIG. 2,
except as described below. Referring to FIGS. 1-8, the casing check valve
850 of FIG. 8 is not at the distal end of the casing string 124. Instead,
in addition to the casing check valve 850 being coupled to a casing pipe
125 at the top portion 832 of the housing body 856, the casing check
valve 850 is also coupled to another casing pipe 125 at the bottom
portion 834 of the housing body 856.

[0094] The bottom portion 834 of the housing body 856 can be coupled to a
casing pipe 125 using one or more of a number of coupling features 873
disposed on and/or between the bottom surface 855 and/or the inner
surface 893. The coupling feature 899 can be the same as, or different
than, the coupling feature 873 of the top portion 832 of the housing body
856. By having the casing check valve 850 disposed within, rather than at
the distal end of, the casing string 124, the point at which the wellbore
120 is isolated by the casing check valve 850 can be controlled. In
addition, multiple casing check valves can be disposed at various points
along the casing string 125 to isolate multiple zones of the wellbore
120.

[0095] When the bottom portion 834 of the housing body 856 includes a
coupling feature 873 to coupling the casing check valve 850 to a casing
pipe 125, the thickness of the portion of the bottom portion 834 that is
clear of the movement of the flapper assembly 886 can be increased
compared to the thickness of the bottom portion 234 of the housing body
256 of the casing check valve 250 of FIG. 2. For example, the thickness
of the portion of the bottom portion 834 that is clear of the movement of
the flapper assembly 886 can be substantially the same as the thickness
of the top portion 832 of the housing body 856, so that the inner surface
893 of the bottom portion 834 forms a diameter 242 that is substantially
the same as the diameter 242 formed by the inner surface 252 of the top
portion 832.

[0096] FIG. 9 is a flowchart presenting a method 900 for isolating a
section of a wellbore using a casing check valve in accordance with
certain example embodiments. While the various steps in this flowchart
are presented and described sequentially, one of ordinary skill will
appreciate that some or all of the steps may be executed in different
orders, may be combined or omitted, and some or all of the steps may be
executed in parallel. Further, in one or more of the example embodiments,
one or more of the steps described below may be omitted, repeated, and/or
performed in a different order. In addition, a person of ordinary skill
in the art will appreciate that additional steps not shown in FIG. 9, may
be included in performing this method. Accordingly, the specific
arrangement of steps should not be construed as limiting the scope.

[0097] Referring now to FIGS. 1-9, the example method 900 begins at the
START step and proceeds to step 902, where a coupling feature 106 of an
operating tool 107 is received. In certain example embodiments, the
operating tool 107 is part of a tubing string 114. The coupling feature
106 (also called a complementary coupling feature 106 above) can be
coupled to an operating tool coupling feature 266 of an actuating sleeve
260 of a casing check valve 250. When this occurs, the actuating sleeve
260 is in some position (e.g., actuated position, normal position)
relative to the housing body 256. The position of the actuating sleeve
260 corresponds to a state of the flapper assembly. Specifically, when
the actuating sleeve 260 is in the normal position, the flapper assembly
286 is in a closed state, and when the actuating sleeve 260 is in the
actuated position, the flapper assembly 286 is in an open state. When the
flapper assembly 286 is in the closed state, the casing check valve is
closed, and when the flapper assembly 286 is in the open state, the
casing check valve is open.

[0098] In step 904, the actuating sleeve 260 is repositioned within a
housing body 256 from a first position to a second position. In certain
example embodiments, the actuating sleeve 260 is repositioned based on
movement of the operating tool 107 in a direction (e.g., toward the
surface 102, toward the open hole portion 127 of the wellbore 120).
Repositioning the actuating sleeve 260 from the first position (e.g., the
normal position) to the second position (e.g., the actuated position)
changes a flapper assembly 286 from a first state (e.g., the closed
state) to a second state (e.g., the open state).

[0099] In step 906, the coupling feature 106 of the operating tool 107 is
released. The coupling feature 106 can be released by (decoupled from)
the operating tool coupling feature 266 of the actuating sleeve 260.
Releasing the coupling feature 106 can be based on continued movement of
the operating tool 107 in the same direction that it was moving in step
904. The coupling feature 106 can be decoupled from the operating tool
coupling feature 266 based on the mechanical forces (e.g., the bottom
surface 258 of the actuating sleeve 260 abutting against the flapper seat
239 of the housing 298), hydraulic forces (e.g., operation of the control
unit 109 using the hydraulic operating control line 121), or some other
means. When the coupling feature 106 of the operating tool 107 is
released, the coupling feature 106 can be retracted. When the coupling
feature 106 of the operating tool 107 is released, the casing check valve
250 maintains its position until the operating tool 107 passes in the
opposite direction, at which time the method 900 can be repeated. Once
step 906 is completed, the process ends with the END step.

[0100] By performing the method 900 of FIG. 9, the casing check valve 250
can be used in one or more of a number of applications that requires
isolating (e.g., in terms of pressure) portions of a wellbore 120. For
example, embodiments of a casing check valve 250 described herein can
isolate at least a distal portion of a casing string 124 and an open hole
portion 127 of the wellbore 120 beyond the casing string 124. The casing
check valve 250 can allow the tubing string 114 (including the BHA 101)
to be tripped above the casing check valve 250 with the hydrostatic
pressure of the mud column in the cavity 123 of the casing string 124
above the casing check valve 250 to be equal to, greater than
(overbalanced), or less than (underbalanced) the open hole pressure below
the casing check valve 250. In certain example embodiments, multiple
casing check valves 250 can be part of and/or disposed along the length
of the casing string 124 to provide redundancy and/or to isolate various
sections of the wellbore 120 that are cased and/or open hole relative to
each other.

[0101] The systems, methods, and apparatuses described herein allow for
isolating one portion of the wellbore from the other portion of the
wellbore. By isolating portions of the wellbore, the integrity of the
wellbore (particularly the open hole portion of the wellbore) can be
maintained. For example, example casing check valves can be utilized to
prevent flow from the open hole portion of the wellbore up into the cased
hole section of the wellbore when making a trip with the tubing string
above the depth of the casing check valve in the wellbore. The example
casing check valve described herein can allow the pressure below the
casing check valve (the open hole portion of the wellbore) to be greater
than the pressure above the casing check valve, enhancing tripping
execution for underbalanced drilling operations. The example casing check
valve can be closed mechanically (e.g., using the distal extension of the
actuating sleeve) to prevent flow while tripping rather than requiring
flow to activate the flapper assembly.

[0102] Example embodiments do not operate using hydraulic pressure, and so
example casing check valves are not limited by hydrostatic pressure.
Since the size of the flapper assembly of an example casing check valve
can be at least as great as an inner diameter of adjacent casing pipe,
the size of a casing check valve can be used with one of a number (within
a range) of sizes of casing pipe. In addition, example embodiments help
promote safety of personnel and equipment during a field operation, such
as tripping, logging, and maintenance.

[0103] Although embodiments described herein are made with reference to
example embodiments, it should be appreciated by those skilled in the art
that various modifications are well within the scope and spirit of this
disclosure. Those skilled in the art will appreciate that the example
embodiments described herein are not limited to any specifically
discussed application and that the embodiments described herein are
illustrative and not restrictive. From the description of the example
embodiments, equivalents of the elements shown therein will suggest
themselves to those skilled in the art, and ways of constructing other
embodiments using the present disclosure will suggest themselves to
practitioners of the art. Therefore, the scope of the example embodiments
is not limited herein.